These days speciality glass is available;
Museum glass blocks UV light, which causes a print to fade.
It also has non-reflective properties, and at certain angles looks almost invisible.
It has to be pointed out that although this glass is good to protect the work,
Most damage will have already been done, as the prints are 40-90 years old, UV blocking glass was not available,
It is essential to buy a print that has been carefully looked after and not exposed to bright sunlight for years.
As the technology of printing was much less sophisticated than it is today;
there were no light fast inks, and acid free paper, which makes the print very susceptible to fading.
Please see the images below..
Some titles were much more susceptible to fading than others due to the quality of inks.